1. Field of the Invention
The present invention relates to lighting technology and more particularly, to a lighting device, which extends the luminous range of the light-emitting devices thereof, enhances the luminance and reduce light loss.
2. Description of the Related Art
The invention of lamp changes the living style of human beings, enabling people to work at night. Nowadays, many different types of lamps have been created for different applications, for example, fluorescent lamps, desk lamps, wall lamps and ceiling lamps for indoor lighting, street lights for outdoor lighting and signal lights for traffic guide and warning applications. Regular outdoor lights commonly emit light through 360° angle. During operation, the light intensity reduces gradually in all directions from the center area toward the distal area, shortening the luminous range. Thus, the number of lamps must be relatively increased to maintain the desired brightness in all areas. However, increasing the number of lamps relatively increases the installation cost and power consumption. Nowadays, in view of the world trend of energy-saving and carbon-reduction, power-saving bulbs and LEDs (light emitting diodes) are intensively used to substitute for conventional lamp bulbs or lamp tubes. However, conventional lighting devices, either for indoor application or outdoor application, still have numerous drawbacks as follows:
1. In consideration of the limited luminous range of conventional street lights, the installation interval must be shortened to maintain the desired luminance; however increasing the number of street lights relatively increases the consumption of power supply.
2. Due to the drawback of limited luminous range of conventional indoor lighting devices, the number of lighting devices in an indoor space must be relatively increased to maintain the desired luminance; however increasing the number of indoor lighting devices relatively increases the installation cost and the consumption of power supply.
3. Due to the limitation that the luminous area of conventional indoor lighting devices and outdoor lighting devices is a circular area, the brightness in the circular luminous area is not uniform, lowering the effect of illumination.
Therefore, it is desirable to provide a lighting device, which eliminates the aforesaid problems.